<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
<!--  开发版本  -->
    <link rel="stylesheet" href="static/plugins/bootstrap-3.4.1/css/bootstrap.css">

<!--  生产版本  -->
    <link rel="stylesheet" href="static/plugins/bootstrap-3.4.1/css/bootstrap.min.css">
</head>
<body>

    <input type="button" value="提交">
    <input type="button" value="提交" class="btn-primary">
    <input type="button" value="提交" class="btn-success">
    <input type="button" value="提交" class="btn-danger btn-xs">

</body>
</html>